dm: avoid a possible __vmalloc deadlock
__vmalloc doesn't fully respect gfp flags (see commit
502624bdad3dba45dfaacaf36b7d83e39e74b2d2) for explanation.
So we need to set noio flag with memalloc_noio_save().
This should be backported to stable kernels 3.8 and newer. The kernel 3.8
doesn't have memalloc_noio_save(), so we should set and restore process
flag PF_MEMALLOC instead.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxx
---
drivers/md/dm-ioctl.c | 3 +++
1 file changed, 3 insertions(+)
Index: linux-3.9.4-fast/drivers/md/dm-ioctl.c
===================================================================
--- linux-3.9.4-fast.orig/drivers/md/dm-ioctl.c 2013-06-07 15:28:59.000000000 +0200
+++ linux-3.9.4-fast/drivers/md/dm-ioctl.c 2013-06-07 15:29:46.000000000 +0200
@@ -1686,7 +1686,10 @@ static int copy_params(struct dm_ioctl _
}
if (!dmi) {
+ unsigned noio_flag;
+ noio_flag = memalloc_noio_save();
dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH, PAGE_KERNEL);
+ memalloc_noio_restore(noio_flag);
if (dmi)
*param_flags |= DM_PARAMS_VMALLOC;
}
--
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